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SECTION I - INFECTIOUS AGENT
NAME: Venezuelan equine encephalitis virus
SYNONYM OR CROSS REFERENCE: Venezuelan equine encephalomyelitis, VEE, Venezuelan equine fever, arbovirus.
CHARACTERISTICS: Togaviridae, alphavirus; 70 mm diameter, ssRNA, enveloped.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Influenza-like manifestations; abrupt onset of severe headache, chills, fever, myalgia,
retro-orbital pain, nausea and vomiting; conjunctival and pharyngeal injection; most infections mild with symptoms
3-5 days; some cases have diphasic fever, CNS involvement, encephalitis with disorientation, convulsions, paralysis,
coma and death.
EPIDEMIOLOGY: Endemic in northern South America, Trinidad, Central America, Mexico and Florida; appear as
epizootics principally in Northern and Southwestern America; in 1970-7 1, spread through Central America into the
USA.
HOST RANGE: Humans, horses.
INFECTIOUS DOSE: 1 viral unit - subcutaneous.
MODE OF TRANSMISSION: Bite of infected mosquito; laboratory infections by aerosols are common.
INCUBATION PERIOD: Usually 2-6 days, can be as short as I day.
COMMUNICABILITY: Human cases are infectious for mosquitoes for 72 hours; mosquitoes are infectious for life;
person-to-person transmission may occur but has not been demonstrated.
SECTION III - DISSEMINATION
RESERVOIR: Rodent-mosquito cycle maintains the enzootic subtypes; epizootic subtypes transmitted in cycles
involving horses, mosquitoes, humans.
ZOONOSIS: Yes, from infected horses via mosquitoes.
VECTORS: Mosquitoes - species within the genus Culex, Aedes, Mansonia, Psorphora, Haemogogus, Sabethes,
Anopheles.
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: N/A
SUSCEPTIBILITY TO DISINFECTANTS:
PHYSICAL INACTIVATION: Inactivated by moist and dry heat; drying.
SURVIVAL OUTSIDE HOST: Virus is present in pharyngeal secretions and is stable when aerosolized, stable
in dried blood and exudates.
SECTION V - MEDICAL
SURVEILLANCE: Monitor for symptoms; confirm by virus isolation, antibody titer.
FIRST AID/TREATMENT: No specific treatment, supportive measures.
IMMUNIZATION: Investigational attenuated virus vaccine is available and recommended for all personnel working
with VEE, infected animals or entering rooms where these agents or infected animals are present.
PROPHYLAXIS: None
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: 150 reported laboratory infections with I death; eighth most commonly
reported laboratory infection.
SOURCES/SPECIMENS: Blood, nasopharyngeal specimens, CSF, urine.
PRIMARY HAZARDS: Exposure to aerosols of infectious solutions and animal's bedding, accidental parenteral
inoculation, broken skin contact.
SPECIAL HAZARDS: Virus is stable in dried blood or exudates.
SECTION VII - RECOMMENDED PRECAUTIONS
CONTAINMENT REQUIREMENTS: Biosafety level 3 practices (with vaccination), containment equipment, and
facilities for activities using animals, arthropods, or potentially infectious clinical materials and infected
tissue cultures.
PROTECTIVE CLOTHING: Laboratory coat; gloves and gown with ties in back and tight wrists when working with
agent.
OTHER PRECAUTIONS: HEPA filtration of all exhaust air prior to discharge; vaccination of workers.
SECTION VIII - HANDLING INFORMATION
SPILLS: Allow aerosols to settle; wearing protective clothing (respirator), gently cover spill with paper
towel and apply 1% sodium hypochlorite (20% commercial bleach), starting at perimeter and working towards the center;
allow sufficient contact time before clean up (30 min.).
DISPOSAL: Decontaminate before disposal; incineration, steam sterilization.
STORAGE: In sealed containers that are appropriately labeled (in locked level 3 facility).
Date prepared: October 11, 1997 Prepared by: Canadian Office of Biosafety.
Information edited by the Colorado State University Office of Biosafety; June 16, 1998.
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